1. Field of the Invention
This invention relates generally to valves and more particularly, but not by way of limitation, to a check valve particularly designed and constructed for facilitating repair and maintenance of the valve when worn or otherwise damaged.
2. Brief Description of Related Art
Check valves are old and well known for use in flow lines where it is desirable to permit fluid flow in one direction and preclude fluid flow in the opposite direction. A common structure for achieving one-way flow is by the use of a disk or clapper that is positioned so that it can pivot about an axis of a pivot shaft. The disk is loosely retained in position between a recess formed in the valve body and the lower edge of a bonnet used to close an access port.
In non-corrosive applications, such a structure generally allows for a reasonable service life. In most applications, however, in particular petroleum production, corrosive constituents generally exist within the flow media. Even when the flow media is only mildly corrosive, the combined action of the corrosion and the erosion created by vibration and the rubbing movement of the pivot shaft against the valve body and the bonnet often causes a loss of surrounding metal which may result in failure of the valve due to misalignment of the disk. One solution to this problem would be to make the entire valve from stainless steel or some other corrosion resistant material. While this would solve the corrosion problem, the cost of the valve would greatly increase and would not be economically viable.
To this end, a need exists for an improved check valve that is capable of being used in a corrosive environment yet is cost effective to manufacture and repair. It is to such an improved check valve that the present invention is directed.